PERTH, Australia — An Australian ship detected two distinct, long-lasting sounds underwater that are consistent with the pings from aircraft black boxes in a major break in the month-long hunt for the missing Malaysia Airlines jet, the search coordinator said Monday.

Navy specialists were urgently trying to pick up the signal again so they can triangulate its position and go to the next step of sending an unmanned miniature submarine into the depths to try to identify plane wreckage.

Confirmation that the signals picked up by the Australian navy ship Ocean Shield belong to Flight 370's black boxes could take days, but the discovery offers "a most promising lead" yet, said Angus Houston, the head of a joint agency coordinating the multinational search. They were stronger and lasted longer than faint signals a Chinese ship reported hearing farther south in the search zone in the remote Indian Ocean.